Specialized tools are necessary to evaluate skeletal phenotypes of transgenic and knockout mouse models. The Skeletal Phenotyping Core, under the direction of Dr. Quarles, has developed the necessary procedures and services to perform in vitro and in vivo analysis of mouse models. The major functions of the Core are to provide: 1) skeletal imaging using X-ray, DEXA and microQCT;and 2) bone tissue processing for quantitative histology, immunohistochemistry, and in situ hybridization. In addition, the Core provides additional services as needed, including assessment of biomarkers in serum;real-time PCR for differential gene expression profiling of bone;cell culture models for assessing osteoblastic function ex vivo;and a mouse clinical research unit for physiological, pharmacological, genetic and surgical interventions. Finally, the Core will serve as a resource for consultation and training of Center investigators in the principles, methods and analyses of bone tissue histology.